A common error message of this is "MAX30102.h header file is missing, or " max30102.h: No such file or directory". There are multiple possible solutions to this error.
Solution 1:
Ensure the beginning of the RD117_Arduino.ino file contains the headers
#include <Arduino.h>
#include "algorithm.h"
#include "max30102.h"
Solution 2:
From here, in the compiler select 'Sketch' from the toolbar then 'Include library > Add .zip libraries...". This will open windows file explorer in which you can install the MAX30102 and algorithm libraries from the .zip downloaded on the MAXREFDES117 website.
Solution 3:
Ensure all header, .ino and .cpp files are contained in the same folder.